Control means for concrete laying machines



March 30,1965 Y H. CHENEY 3,175,477

CONTROL MEANS FOR CONCRETE LAYING MACHINES Filed Dec. 6, 1960 2Sheets-Sheet 1 l-I l! CONTROL MEANS FOR CONCRETE LAYING MACHINES FiledDec. 6. 1960 2 Sheets-Sheet 2 United States Patent 3,175,477 CONTROLMEANS FOR CONCRETE LAYING MACHINES Alwyn Halley Cheney, 23 VancouverAve., Springbank,

This invention relates to control means for concrete laying machines.

It is already known to lay concrete by means of machines which moveforward to leave the concrete in position, and as an example referencemay be had to my earlier applications upon which Australian Patents224,-

413 and 228,818 have issued.

From attempts which have been made earlier at laying pipes or curbing orthe like, it has been shown that a large number of requirements must bemet to achieve a satisfactory product. One great difiiculty which existsin getting satisfactory operation is removal of variations in theforward speed of the machine which lays the pipes or curbing or the likeand inconsistencies in the feed of concrete aggregate or other material.

In cases where a switch or valve is used to provide an on-off controlfor drive means for a concrete laying machine, the inertia of themachine in stopping and starting introduces wide variations in pressurein the concrete being packed. I have found that for most purposes asuitable pressure is sixty pounds per square inch applied to a wet mixof concrete being packed. If the pressure variation is maintained withinplus or minus five pounds per square inch, a homogeneous product isformed, and after three weeks of ageing, a compressive strength ofapproximately six thousand pounds per square inch for a standard 4:2:1mix has been achieved. If the pressure is allowed to fall below fortypounds per square inch, the strength decreases, while if the pressureexceeds eighty pounds per square inch, practical difliculties areencountered in the extrusion or packing of the wet mix.

The present invention seeks to overcome the difficulties which have beenexperienced heretofore in maintaining a comparatively steady pressure onconcrete being packed to achieve a homogeneous and suitable productwhich will have the necessary strength throughout its length and inwhich variation of the product along its length will be reduced to safevalues or will be completely removed.

According to my invention the improved product is attained by controlmeans wherein forward motion of the machine is through a variable speeddrive controlled through pressure sensitive means actuated by thepressure built up in the packed flowable material whereby a relativelyuniform selected pressure is maintained on the material but speed of themachine varies in proportion to the volume of flowable material fedthereto.

It will be realized that the actual form of the invention can be verywidely varied within the general spirit thereof, but to enable theinvention to be fully appreciated an embodiment thereof will now bedescribed with reference to the accompanying drawings, in which:

FIG. 1 is a schematic layout of a machine according to the invention,

FIG. 2 is a fragmentary perspective of such a machine, and

FIG. 3 is a central section through a throttle valve and its operatingmechanism.

A machine 1 for laying curbing comprises a former 2 by means of whichthe product is shaped, the aggregate "ice being fed from a suitablehopper 3 to this former 2 by concrete packing means 4 consisting of amandrel 5 surrounded by a helical blade 6 within the former 2, themandrel 5 being driven by the mandrel drive motor 7 to worm the materialfrom the hopper 3 to be extruded through the former 2.

The driven mandrel 5, instead of being simply fixed in bearings, isrotationally carried by bearings 10 which are supported by a pair ofspaced parallel arms 12 'pivotally suspended from the sub-frame 11.Consequently, the mandrel 5 is free to move axially with respect to thesub-frame 11 as it revolves. Axial displacement of the mandrel 5 isresisted and sensed by pressure sensitive means which measures thethrust of mandrel 5 as it forces the aggregate into position in theformer 2.

Flanges on the mandrel 5 prevent axial movement in the bearings 10 sothat variations in the pressure exerted in an axial direction on thehelical blade 6 as it forces the aggregate into the former isproportional to variations in axial displacement of the mandrel 5 withrespect to the sub-frame 11 and such variations are used to vary therate of forward drive of the machine 1.

The pressure within the concrete being packed is transmitted through ahydraulic master cylinder 16 to a hydraulic slave cylinder 17 by anenclosed hydraulic fluid containing line 18. The piston 19 of'the slavecylinder is loaded by spring 20, which spring applies pressure via thehydraulic pressure line 18 to the mandrel 5 of sixty pounds per squareinch over the annular area defined by the helical blade 6. The slavepiston rod 22 is coupled to the arm 23 of the throttle valve 24 which isplaced in a by-pass circuit 25 across a variable speed hydraulic motor26, the pressure hydraulic fluid being supplied by a vane type pump 27driven by a gasoline engine 23. The frame 13 is mounted on wheels 30engaging a track 31, and a chain 32 couples the frame drive motor 26 toone of the wheels 30. When the throttle valve 24 is fully open, itpermits sufiicient by-pass of hydraulic fluid to prevent the frame drivemotor 26 from operating, while if the valve is fully closed, the motor26 operates at the maximum speed determined by the output of the pump27.

It will however be realized that instead of allowing the mandrel itselfto move forwardly to record these pressure factors in accordance withthe above embodiment, the mandrel could be stationary and pressuremeasuring means such as a pressure sensitive finger could be associatedwith the mould itself which forms the curbing or pipe or otherstructure, or the whole of the laying section comprising the mouldingmechanism as well as the feeding mandrel or the like can be mounted onthe travelling frame by means of which it is carried to give pressuresensitive adjustment between this mechanism and the frame which can inturn be used to control the rate of forward drive of the frame.

The form of control to the throttle valve can also vary considerably.The mandrel 5 according to one embodiment is fitted with a thrustbearing against which a spring operates, urging the mandrel 5 in arearward direction, and the plunger of a needle valve is movable withthe thrust bearing, the needle valve functioning as the throttle valve.

One of the arms 12 may be extended upwardly to engage control means,either by means of a by-pass valve as disclosed in the above embodiment,or alternatively by control of the pump, if a pump of the displaceableaxis type is used.

It has been found that when the laying of concrete or the like ispressure controlled by means of this invention, a much better productresults which will be as nearly homogeneous as it is possible to get itand which is free from the cracking or voids which result where theproduct is not packed at the correct pressure.

Where pressure control is adequate it is possible to use a much driermiX for concrete products, the ratio employed being a 0.45 water/cementratio, and this -en- 'sures that pipes or curbing or the like can bepressure moulded under conditions where they'will retain their shapebecause of the minimum amount of water present and therefore much higherfinishes with better guarantee of homogeneity and absence of porositycan be assured. It has been found undesirable for the ratio to lie above0.6 or below 0.3.

The mould 2 may extend beyond the outside of the. helical blade 6, butnot by more than two inches in any' one direction without danger ofstrength and homogeneity loss. The mould 2 may not be disposed inwardlyof the outside of the helical blade 6.

Obviously, instead of moving the machine forward by means of the statedcontrol, the machine could be fixed and the means on which the concreteis being formed moved.

but being axially restrained against relative axial movement in saidbearings, said mandrel being retained parallel to said concrete formerby said spaced parallel arms, a helical blade on the mandrel, a mandreldrive motor coupled to said mandrel and arranged to drive said mandrelcontinuously; and control means comprising: a hydraulic master cylinderincluding a piston between said hinged arms and said frame, ahydraulicslave cylinder including a piston on said frame, an enclosed hydraulicfluid containing pressure transmitting line interconnecting said masterand slave cylinders, a spring betweensaid slave cylinder and the pistontherein, a throttle valve on the main frame coupled to said drive motor,and a link between said slave cylinder piston and said throttle valve,such that axial movement of said mandrel relativeto said frame bothcompresses said spring and also actuates said throttle valve to increasethe speed of said drive motor thereby maintaining substantially uniformpressure on concrete extruded by said mandrel through said formerirrespective of the rate of'concrete feed.

2. A machine according to claim 1 wherein a variable speed hydraulicmotor constitutes said drive motor, the control means further comprisinga hydraulic by-pass circuit across said variable speed from drive motor,said throttle valve being in said by-pass circuit.

.3. A machine according to claim 1 further comprising a hopper openinginto said former for supplyin'g concrete thereto. 7

,4. A machine according to claim 1 wherein said mandrel has a constantdiameter for substantially the entire length thereof. a, 7 I

5. A machine according to claim 1 wherein said helical stant for theentire length thereof.

blade has an outer diameter which is substantially con- References Citedbythe Examiner UNITED STATES PATENTS JACOB L. NACKENOFF,'P'rham'Examiner.

1. A CONCRETE LAYING MACHINE COMPRISING A MAIN FRAME, WHEELS SUPPORTINGSAID MAIN FRAME, A VARIABLE SPEED DRIVE MOTOR ON SAID FRAME COUPLED TOSAID WHEELS FOR DRIVING SAID FRAME, A SUB-FRAME, A CONCRETE FORMERSUPPORTED BY THE SUB-FRAME, A MANDREL EXTENDING INTO SAID FORMER, SPACEDPARALLEL ARMS HAVING UPPER AND LOWER ENDS, SAID ARMS DEPENDING FROM SAIDBEING PIVOTED AT THEIR UPPER ENDS TO SAID SUB-FRAME, BEARINGS SUPPORTEDBY SAID ARMS AT THEIR LOWER ENDS NORMAL TO SAID MANDREL, SAID MANDRELBEING SUPPORTED IN SAID BEARINGS FOR ROTATIONAL MOVEMENT BUT BEINGAXIALLY RESTRAINED AGAINSAT RELATIVE AXIAL MOVEMENT IN SAID BEARINGS,SAID MANDREL BEING RETAINED PARALLEL TO SAID CONCRETE FORMER BY SAIDSPACED PARALLEL ARMS, A HELICAL BLADE ON THE MANDREL, A MANDREL DRIVEMOTOR COUPLED TO SAID MANDREL AND ARRANGED TO DEIVE SAID MANDRELCONTINUOUSLY; AND CONTROL MEANS COMPRISING: A HYDRAULIC MASTER CYLINDERINCLUDING A PISTON BETWEEN SAID HINGED ARMS AND SAID FRAME, A HYDRAULICSLAVE CYLINDER INCLUDING A PISTON ON SAID FRAME, AN ENCLOSED HYDRAULICFLUID CONTAINING PRESSURE TRANSMITTING LINE INTERCONNECTING SAID MASTERAND SLAVE CYLINDERS, A SPRING BETWEEN SAID SLAVE CYLINDER AND THE PISTONTHEREIN, A THROTTLE VALVE ON THE MAIN FRAME COUPLED TO SAID DRIVE MOTOR,AND A LINK BETWEEN SAID SLAVE CYLINDER PISTON AND SAID THROTTLE VALVE,SUCH THAT AXIAL MOVEMENT OF SAID MANDREL RELATIVE TO SAID FRAME BOTHCOMPRESSES SAID SPRING AND ALSO ACTUATES SAID THROTTLE TO INCREASE THESPEED OF SAID DRIVE MOTOR THEREBY MAINTAINING SUBSTANTIALLY UNIFORMPRESSURE ON CONCRETE EXTRUDED BY SAID MANDREL THROUGH SAID FORMERIRRESPECTIVE OF THE RATE OF CONCRETE FEED.